Specifically, though not exclusively, the invention is usefully applied in separating solid particles discharge fluids in dental apparatus.
As is well known, dental aspiration plants remove fluids from the mouth of a patient during an operation. These fluids comprise a gaseous part (generally air), a liquid part (generally water, blood and other liquids which are used in dental apparatus) and a solid part in particle form (usually the amalgam used in fillings). The aspirated fluids contain various polluting substances, such as for example solid particles of amalgam. In dental apparatus the production of polluting fluids can be quite abundant, although generally discontinuous. These fluids, before being discharged into the sewers, must be freed of polluting substances.
The prior art teaches separating the solid particles from the fluids by means of a cyclone separator which exploits the centrifugal force developed by creating a rapid vortex in the fluid flow in which the solid particles are suspended. These cyclone separators comprise a recipient having an inlet for the fluid and an upper outlet for the fluid from which the solid particles have been removed. The separator recipient has a downwards-converging truncoconical shape, at the narrow end of which there is a discharge that can be connected to a container in which the solid particles can be collected.
These separators, of extremely simple construction, operate without any external motor and entirely by the creation of a centrifugal force impressed on the particles to be separated by the fluid movement. The particles to be separated are projected against the walls of the recipient and descend towards the bottom of the separator while the fluid rises in the secondary vortex created in the central part of the separator and exits from the top part of the separator. The degree of separation of the particles greatly depends on the fluid flow rate crossing the centrifuge. With low flow rates, these separators are not able to guarantee a sufficient level of separation of the solid particles which, especially for use in dental apparatus, must be at least 95% of the total of the particles contained in the fluid.
To obviate the above-described drawback, the prior art teaches a cyclone separator, described in EP 0 557 251, by the same applicant. In this separator, the efficiency and performance of the separation are increased thanks to the use of a centrifugal pump the blade of which, located internally of the recipient and above the truncoconical part, can rotate so as to accelerate the speed of the water independently of the flow rate, and thus performs a first separation of the particles by centrifugation. The use of a centrifuge pump, which enables the separator to function both as a centrifuge separator and as a cyclone separator, is however somewhat complicated in construction and therefore expensive.
Furthermore, to pass from xe2x80x9ccentrifugexe2x80x9d to xe2x80x9ccyclonexe2x80x9d operation, the above-described separator requires the use of a solenoid valve commanded by an electrical signal coming from outside the separator, closing or opening the outlet of the separator by a command which is independent of the operative conditions of the separator. This creates yet another constructional complication and also means that the separator is dependent on the functioning of an external device.
European patent application number EP 99830011.5, which published as EP 0 933 066 A2 and is by the same applicant, teaches another solution, which has a special conformation and arrangement of the fluid inlet and outlet holes in the separator. This separator, constructionally very simple, increases the efficiency of the separation, but cannot operate at very slow flow rates.
The main aim of the present invention is to obviate the above-mentioned drawbacks in the prior art by providing a cyclone separator which is constructionally very simple and economical and which at the same time can provide a high degree of separation, independently of the flow rate of the fluid reaching the separator.
An advantage of the device is that there is no need for an auxiliary motor or command signals from the outside of the device to operate it.
A further advantage of the device is that it can be cleaned and maintained by very simple and easy operations.
These aims and more besides are achieved by the object of the invention as it is characterised by the accompanying claims.
The cyclone separator with flow rate regulation is for separating solid particles from a fluid, especially in dental apparatus. The separator comprises a recipient having an inlet for the fluid and an upper outlet for the fluid once the solid particles have been removed therefrom. The separator also comprises a recycling conduit which places an outlet conduit in communication with the inlet, a three-way valve to an inlet of which the outlet conduit is connected, and to outlets of which the recycling conduit and the outlet are connected. The three-way valve has an obturator which can block the connection between the outlet conduit and the recycling conduit, a one-way valve which has an obturator and is located at the outlet downstream of the three-way valve. The one-way valve is normally closed and can connect the outlet conduit with the outlet. The three-way valve and the one-way valve are brought into action when the fluid pressure in outlet from the separator reaches first and second predetermined values.